A franking machine is fitted with data input means generally constituted by a keyboard and a display means commonly referred to as a "display". The user keys in the postage value of a stamp to be printed via the keyboard and the digits keyed in appear in succession in the display, thereby enabling the user to check they are keyed in properly. In addition to its function of checking keying, the display performs two other functions which are:
an alarm function for signalling faults and consisting, for example, in indicating to a user that the machine's credit has been used up (for prepayment type machines) or that the machine has locked up after sensing a fault; this function is generally performed by indicator lamps; and
a function of displaying the machine's meter which accumulates the total value of franking performed since the machine was put into service. In normal operation, the state of the meter is permanently displayed so as to enable simple checks on consumption to be performed. In particular, in socalled "post payment" mode, the state of this counter is copied every day onto a monthly deposit sheet.
In order to provide such a display, most franking machines are equipped with a system for displaying characters in the form of seven segments. This well known technique is capable of properly displaying all digits and a certain number of letters or symbols which are more or less well represented.
In order to assist the user in obtaining better management of franking expenditure, for example by splitting said expenditure between a plurality of accounts, it is important for the franking machine to be equipped with auxiliary meters. These meters are made available to the user and serve to accumulate the total number or the total value of franking operations performed in a given period of time. In order to make use of the auxiliary meters, it is necessary for the user to be able, with respect to each meter taken individually, to specify the meter, to start it, to stop it, to reset it to zero, and to display it. These new features are made available by extending the capabilities of the keyboard, either by fitting it with additional keys or else by authorizing simultaneous action on two or three existing keys. For example, in a machine having two auxiliary meters, e.g. a "Subtotal" meter and a "Piece Count" meter, access is given to these meters by two additional keys. Depressing one of these keys causes the state of the selected meter to appear on the display. In order to reset a selected one of the auxiliary meters to zero, a third key is necessary. Sometimes, in order to avoid providing additional keys, the auxiliary meters are selected and reset to zero by acting simultaneously on two keys: for example "1" and "star" to select the "Subtotal" meter, and "0" and "star" operated simultaneously to reset a previously selected "Subtotal" to zero.
If instead of providing two auxiliary meters, it is desired to offer several auxiliary meters to the user, it then becomes necessary either to greatly increase the number of keys, or else to generalize the technique of double or triple key-presses, in which case it becomes necessary to accompany the machine with a code sheet. The user must then constantly refer to the code sheet in the machine's operating manual in order to select, at any given instant, a particular one of its numerous auxiliary meters. Further, it becomes necessary to provide for an increase in display capacity, for example by providing an additional indicator lamp which switches on whenever the state of an auxiliary meter is being displayed, plus at least two digits specifying the number of the meter.
The above-outlined drawbacks become worse if additional functions are added, for example: displaying the date and the time; displaying out-of-credit; providing a large number of auxiliary meters; and stopping or resetting or starting an auxiliary meter. These additional functions require the use of additional keys and the keyboard becomes complicated to use, inconvenient, confusing for the operator, and requires a certain amount of operator training time.
These drawbacks are avoided in a franking machine having a keyboard with 16 keys enabling ordinary franking operations to be performed and also enabling special operations to be accessed via a Menu key on the keyboard. Each operation, regardless of whether it is a normal operation or a special operation, is constituted by a message which is a text made up of digits, letters, and symbols, with each text being split up into screens, for example screens of two lines by 16 or 20 characters each, and the screens are displayed successively on the display of the machine, with the display being of the alphanumeric type or of the graphic type.
This machine is capable of performing franking once the operator has keyed in the value of the stamp, with the number of franking operations being limited solely by the available credit, and this may be a cause of error if the operator continues franking without changing the value of the stamp.
Preferred embodiments of the invention provide the operator with directly selectable operating modes depending on the number of franking operations to be performed with a given value of stamp.
The operator may also set the number of franking operations that can be performed in one of said modes.